Cannulation of patients' blood vessels occurs for many reasons, including catheterization for the purpose of inserting catheters for imaging and repairing coronary and other arteries, inserting indwelling lines for the purpose of monitoring the patient, for example to obtain continuous blood pressure or measure blood gasses, or for infusing medications. Such cannulation involves locating a blood vessel in which to create a puncture and then inserting a cannula, which may be sheaths for catheterizations or arterial or venous “lines” for monitoring (these may also be known as “art-lines” or “a-lines”), in some cases for an extended period of time. Such sheaths or lines may also provide vascular access for other procedures, for example, drawing blood, inserting a pacemaker lead or performing electrophysiology tests. Blood vessels commonly used for these purposes include the femoral, brachial, jugular, subclavian and radial arteries and veins. The present invention relates to cannulation of the blood vessels in the wrist, more particularly the radial artery or vein.
Immediately prior to cannulating the radial artery, the operator, who is a medical professional, extends the patient's wrist so as to put it into dorsiflexion. Dorsiflexion of the wrist results in lengthening the vessels therein, thereby making them more taut and less susceptible to movement when accessing the vessel for the purpose of puncturing it and inserting a cannula. The radial artery in particular tends to “roll” or move less when performing the puncture, when it is thusly lengthened. It is also thought that sometimes the vessel moves closer to the skin surface when the wrist is put into dorsiflexion. A dorsiflexion angle in the range of 20° to 45° is thought to provide optimal extension for this purpose.
The patient's hand and forearm are also stabilized prior to cannulation, so that the opportunity for the wrist to move is minimized. The hand is usually placed with the dorsal surface facing down, so that the palmar aspect faces up. In this position, the hand naturally tends to pronate, which causes the area of the forearm to be punctured to often be positioned at a disadvantageous angle relative to the longitudinal axis of movement of the needle used to initially gain vascular access.
Properly extending the wrist into dorsiflexion and securement of the forearm and hand such that the puncture site is stable and facing upward with the proper aspect exposed are therefore requirements that must be addressed for safe, successful cannulation to occur.
Use of materials such as rolled up gauze, rolled up towels and surgical drapes, adhesive tape, and other disposable soft goods are often employed to address these requirements. For catheterizations the wrist is often strapped or taped to an arm-board attached to the procedure table. When inserting a-lines for monitoring, cardboard or other relatively stiff materials are often used in an attempt to address these requirements. Increasingly, braces specifically designed to address these requirements have been developed, including the Hand-Aid product marketed by Kimberly-Clark. Though somewhat effective, the Hand-Aid does not provide good stability or securement since it has rounded ends that encourage side-to-side rolling when placed on a flat surface, and also permits rolling of the forearm and hand when it is deployed onto the patient. Further, it has a relatively shallow dorsiflexion angle.